321E.32  Movement of structures.
  The weight limits on axles used for the movement of physical structures and buildings shall be subject to the same weight limits which are placed on all other axles. However, when physical structures or buildings are moved and the axles under the load are five feet or more apart, each axle shall be considered a separate axle in determining the axle weight limitations provided by law.
88 Acts, ch 1208, §4